The 2008 World Health Organization (WHO) classification is used to diagnose MDS. Patients diagnosed with MDS are stratified into one of five risk categories, based on a prognostic score calculated according to the revised International Prognostics Scoring System (IPSS-R): very-low risk, low risk, intermediate risk, high risk, and very-high risk. IPSS-R scores are estimated from percent of bone marrow blasts, number and depth of cytopenias, and presence of specific cytogenetic abnormalities, collectively reflecting the total number of risk factors.